Printwear

October '16

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P R I N T W E A R O C T O B E R 2 0 1 6
What are some of the advantages of
using honeycomb aluminum platens
on an automatic press versus the
more traditional heavy metal type?
Traditional metal platens are heavy. As an au-
tomatic press starts and stops, this weight puts
extra stress on the motor. Another issue is that,
especially during flashing, heavy metal retains
heat, which can cause issues with premature
gelling of water-based inks during production.
Honeycomb platens are made of aluminum,
so they are both light and hollow. The honey-
comb pattern provides mechanical resistance,
allowing it to endure millions of press rotations.
In addition, aluminum is a much easier metal
for controlling the temperature of the platen,
and consequently is a better choice when using
water-based inks. What's more,
honeycomb platens arguably hold
sharper details and finer dots.
JEFFREY PAUL, RYONET
Honeycomb platens can
help prevent premature
gelling of water-based inks
and can last through mil-
lions of press rotations.
(Image courtesy Ryonet)
What kind of exposure unit is best for a screen-printing
operation?
As with most screen-printing equipment decisions, the "best" choice in exposure
units depends on your budget, capacity, and type of printed graphics.
The lowest-cost option is a fluorescent exposing unit for a reason: fluorescent
UV bulbs are relatively inexpensive but weak, requiring long exposure times. A
larger drawback, however, is the scattered nature of fluorescent light, which ema-
nates 360 degrees from the bulb, causing light to pass through the glass at angles
ranging from 90 to 200 degrees. The lower the angle of light, the more it under-
cuts the film positive, reducing edge sharpness of the stencil and printed image.
To reduce long exposure times, fluorescent bulbs typically are positioned close to
the glass, which worsens the problem of undercutting.
Units with LED bulbs are more expensive initially, but offer superior effec-
tiveness in several ways. First, they project bright light directionally, and can be
positioned farther from the glass, achieving significantly greater "columniation,"
or light projected perpendicular to the glass, with the least amount of undercut-
ting. They also offer uniform spacing and emit precise wavelengths of LED light.
As a result, exposures are 10 to 15 times faster than with fluo-
rescent bulbs, more uniform from edge to edge, and significantly
sharper, especially with smaller type and process-color halftones.
MARK VASILANTONE, VASTEX
SCREEN PRINTING